Cylinder direct injection spark-ignition engine

Abstract

A cylinder direct injection spark-ignition engine in which fuel is directly injected into each cylinder. The engine comprises intake and exhaust valves movably disposed to a cylinder head. A piston is movably disposed in a cylinder in a cylinder block so as to define a combustion chamber. The piston is formed at its piston crown with a generally circular cavity having a center axis which is offset from a center axis of the piston toward the intake valve. A spark plug is provided such that its tip end section is disposed above a part of a peripheral portion of the circular cavity which part is located closer to the center axis of the piston than to periphery of the piston. A device for generating swirl of intake air in the combustion chamber is provided. A fuel injector valve is provided to directly inject fuel into the combustion chamber and has an axis which inclines relative to a bottom flat surface of the cylinder head and gradually approaches the bottom flat surface in a direction from the intake valve to the exhaust valve. The fuel injector valve has a fuel ejection hole whose axis inclines relative to the axis of the fuel injector valve so as to form a first angle which is smaller than a second angle formed by the axis of the fuel injector valve, relative to the bottom flat surface of the cylinder head.

What is claimed is: 
     
       1. A cylinder direct injection spark-ignition engine, comprising: intake and exhaust valves movably disposed on a cylinder head which defines a portion of a combustion chamber; and   a fuel injector valve for directly injecting fuel into the combustion chamber, the fuel injector valve having an axis inclined relative to a bottom surface of the cylinder head and th gradually approaches the bottom surface in a direction extending from an intake valve side of the combustion chamber toward an exhaust valve side of the combustion chamber, the fuel injector valve having a fuel ejection hole with an axis inclined relative to the axis of the fuel injector valve so as to form a first angle which is smaller than a second angle formed by the axis of the fuel injector valve and the bottom surface of the cylinder head,   wherein the fuel injector valve is arranged such that fuel injected through the fuel ejection hole is formed into a shape of a spray cone having first and second sections which are opposite to each other with respect to a plane containing the axis of the fuel ejection hole, the first section being located closer to a surface of the cylinder head defining a portion of the combustion chamber than the second section, the first section having a higher flow velocity than the second section.   
     
     
       2. A cylinder direct injection spark-ignition engine, comprising: intake and exhaust valves movably disposed on a cylinder head;   a piston movably disposed in a cylinder in a cylinder block so as to define a portion of a combustion chamber, the piston having a piston crown with a generally circular cavity having a center axis which is offset from a center axis of the piston toward the intake valve;   a spark plug having a tip end section disposed above a part of a peripheral portion of the circular cavity which part is located closer to the center axis of the piston than to a periphery of the piston;   a device for generating a swirl of intake air in the combustion chamber; and   a fuel injector valve for directly injecting fuel into the combustion chamber, the fuel injector valve having an axis inclined relative to a bottom surface of the cylinder head and that gradually approaches the bottom surface in a direction extending from an intake valve side of the combustion chamber toward an exhaust valve side of the combustion chamber, the fuel injector valve having a fuel ejection hole with an axis inclined relative to the axis of the fuel injector valve so as to form a first angle which is smaller than a second angle formed by the axis of the fuel injector valve and the bottom surface of the cylinder head,   wherein the fuel injector valve is arranged such that fuel infected through the fuel ejection hole is formed into a shape of a spray cone having first and second sections which are opposite to each other with respect to a plane containing the axis of the fuel ejection hole, the first section being located closer to a surface of the cylinder head defining a portion of the combustion chamber than the second section, the first section having a higher flow velocity than the second section.   
     
     
       3. A cylinder direct injection spark-ignition engine as claimed in claim 2, wherein the cylinder head has first and second intake ports and first and second exhaust ports for the cylinder, and the swirl generating device includes a swirl control valve disposed to control air flow in the first intake port in accordance with an engine operating condition. 
     
     
       4. A cylinder direct injection spark-ignition engine, comprising: a cylinder block having a plurality of cylinders;   a cylinder head mounted on a block deck of the cylinder block, the cylinder head having first and second intake ports and first and second exhaust ports for at least one cylinder;   first and second intake valves movably disposed on the cylinder head, the first and second intake ports being closable respectively by the first and second intake valves, and first and second exhaust valves movably disposed on the cylinder head, the first and second exhaust ports being closable respectively by the first and second exhaust valves;   a fuel injector valve for directly injecting fuel into a combustion chamber in the at least one cylinder, the fuel injector valve having an axis inclined relative to the block deck of the cylinder block and that gradually approaches the block deck in a direction extending from an intake valve side of the combustion chamber toward an exhaust valve side of the combustion chamber, the fuel injector valve having a fuel ejection hole with an axis inclined relative to the axis of the fuel injector valve so as to form a first angle which is smaller than a second angle formed by the axis of the fuel injector valve and the block deck of the cylinder block;   a spark plug having a tip end section projecting into the combustion chamber;   a piston movably disposed in the at least one cylinder to define location of the combustion chamber between it and the cylinder head, the piston having a piston crown with a generally circular cavity having a center axis which is offset from a center axis of die piston toward the intake valves; and   a swirl control valve disposed to control air flow in the first intake port in accordance with an engine operating condition;   wherein the second intake port has an axis with at least a major part contained in a first vertical plane inclined relative to a second vertical plane to form a first predetermined angle, the first vertical plane gradually approaching the center axis of the piston in a direction toward the combustion chamber relative to the second vertical plane, the first and second vertical planes being vertical to the block deck of the cylinder block, the second vertical plane passing through the first intake and exhaust valves and being perpendicular to a third vertical plane containing the center axes of the cylinders, the first intake and exhaust valves being located respectively on opposite sides of the third vertical plane.   
     
     
       5. A cylinder direct injection spark-ignition engine as claimed in claim 4, wherein the first vertical plane is generally tangential to a periphery of the circular cavity. 
     
     
       6. A cylinder direct injection spark-ignition engine as claimed in claim 4, wherein the first vertical plane is generally parallel with a fourth vertical plane containing a tangent line of a periphery of the circular cavity. 
     
     
       7. A cylinder direct injection spark-ignition engine as claimed in claim 4, wherein the tip end section of the spark plug is disposed above a peripheral portion of the circular cavity and located on an opposite side of the first vertical plane with respect to the second vertical plane. 
     
     
       8. A cylinder direct injection spark-ignition engine as claimed in claim 4, wherein the first vertical plane passes through a space between a periphery of the circular cavity and the spark plug. 
     
     
       9. A cylinder direct injection spark-ignition engine as claimed in claim 4, wherein the axis of the fuel injector valve is directed into the circular cavity, the fuel injector valve being located between the first and second intake ports. 
     
     
       10. A cylinder direct injection spark-ignition engine as claimed in claim 4, wherein the swirl control valve is arranged to substantially block the first intake port under a predetermined engine operating condition in which stratified charge combustion is made in the combustion chamber. 
     
     
       11. A cylinder direct injection spark-ignition engine as claimed in claim 4, wherein the first and second intake ports are located on an opposite side of the third vertical plane with respect to the first and second exhaust ports. 
     
     
       12. A cylinder direct injection spark-ignition engine as claimed in claim 4, wherein the first predetermined angle is at least 5 degrees and smaller than 15 degrees. 
     
     
       13. A cylinder direct injection spark-ignition engine as claimed in claim 4, wherein the at least a major part of the axis of the second intake port forms a second predetermined angle relative to the block deck of the cylinder block, the second predetermined angle being within a range of larger than 30 degrees and smaller than 40 degrees. 
     
     
       14. A cylinder direct injection spark-ignition engine as claimed in claim 4, wherein the second angle is within a range of from 35 degrees to 45 degrees. 
     
     
       15. A cylinder direct injection spark-ignition engine, comprising: a cylinder head that defines a portion of a combustion chamber and that holds a spark plug;   at least one intake valve and at least one exhaust valve movably disposed on the cylinder head; and   a fuel injector that directly injects fuel into the combustion chamber, the fuel injector having an axis inclined relative to a plane forming a right angle with a longitudinal axis of the combustion chamber and that injects fuel from an intake valve side of the combustion chamber toward an exhaust valve side of the combustion chamber, the fuel injector having a fuel ejection hole with an axis inclined relative to the axis of the fuel injector toward the spark plug,   wherein the fuel injector is arranged such that fuel injected through the fuel ejection hole has first and second sections on opposite sides of a plane containing the axis of the fuel ejection hole, the first section being located closer to the spark plug than the second section, the first section having a higher flow velocity than the second section.   
     
     
       16. A cylinder direct injection spark-ignition engine as claimed in claim 15, wherein the fuel injector injects fuel into the combustion chamber in the shape of a hollow cone. 
     
     
       17. A cylinder direct injection spark-ignition engine as claimed in claim 15, wherein the axis of the fuel ejection hole is substanlially contained in a plane passing through a tip end section of the spark plug. 
     
     
       18. A cylinder direct injection spark-ignition engine as claimed in claim 15, wherein the fuel injector has only one fuel ejection hole. 
     
     
       19. A cylinder direct injection spark-ignition engine as claimed in claim 15, wherein the injected fuel defines a spray angle that is greater than an angle of inclination between the axis of the fuel injector and the axis of the fuel ejection hole. 
     
     
       20. A cylinder direct injection spark-ignition engine as claimed in claim 15, wherein the fuel injector injects fuel above and below the axis of the fuel injector. 
     
     
       21. A cylinder direct injection spark-ignition engine as claimed in claim 15, wherein the fuel injector injects fuel during a compression stroke when stratified charge combustion occurs. 
     
     
       22. A cylinder direct injection spark-ignition engine as claimed in claim 15, further comprising: a first intake port and second intake port in the cylinder head; and   a piston having a cavity,   wherein an axis of the second intake port lies within a first plane and the first plane is generally tangential to a periphery of the cavity.   
     
     
       23. A cylinder direct injection spark-ignition engine, comprising: a cylinder head that defines a portion of a combustion chamber and that holds a spark plug;   a cylinder block having a cylinder;   at least one intake valve and at least one exhaust valve movably disposed on the cylinder head;   a piston movably disposed in the cylinder so as to define a portion of the combustion chamber, the piston having a piston crown with a generally circular cavity having a center axis, which is offset from a center axis of the piston toward the intake valve;   a spark plug having a tip end section disposed above a part of a peripheral portion of the circular cavity, which part is located closer to the center axis of the piston than to a periphery of the piston;   a device that generates a swirl of intake air in the combustion chamber; and   a fuel injector that directly injects fuel into the combustion chamber, the fuel injector having an axis inclined relative to a plane forming a right angle with a longitudinal axis of the combustion chamber and that injects fuel from an intake valve side of the combustion chamber toward an exhaust valve side of the combustion chamber, the fuel injector having a fuel ejection hole with an axis inclined relative to the axis of the fuel injector toward the spark plug;   wherein the fuel injector is arranged such that fuel injected through the fuel ejection hole has first and second sections which are on opposite sides of a plane containing the axis of the fuel ejection hole, the first section being located closer to the spark plug than the second section, the first section having a higher flow velocity than the second section.   
     
     
       24. A cylinder direct injection spark-ignition engine as claimed in claim 23, wherein the cylinder head includes first and second intake ports and first and second exhaust ports for the cylinder, and the swirl generating device includes a swirl control valve disposed to control air flow in the first intake port in accordance with an engine operating condition. 
     
     
       25. A cylinder direct injection spark-ignition engine as claimed in claim 24, wherein the swirl control valve is open during homogeneous charge combustion and closed during stratified charge combustion. 
     
     
       26. A cylinder direct injection spark-ignition engine, comprising: a cylinder block having a block deck and a plurality of cylinders that each define a combustion chamber;   a cylinder head mounted on the block deck, the cylinder head having first and second intake ports and first and second exhaust ports for at least one of the cylinders;   first and second intake valves movably disposed on the cylinder head to open and close the first and second intake ports;   first and second exhaust valves movably disposed on the cylinder head to open and close the first and second exhaust ports;   a spark plug having a tip end section projecting into the combustion chamber defined by the at least one cylinder;   a fuel injector that directly injects fuel into the combustion chamber, the fuel injector having an axis inclined relative to a plane forming a right angle with a longitudinal axis of the at least one cylinder and that injects fuel from an intake valve side of the combustion chamber toward an exhaust valve side of the combustion chamber, the fuel injector having a fuel ejection hole with an axis inclined relative to the axis of the fuel injector toward the spark plug;   a piston movably disposed in the at least one cylinder to define a portion of the combustion chamber, the piston having a piston crown with a generally circular cavity having a center axis which is offset from a center axis of the piston toward the intake valves; and   a swirl control valve disposed to control air flow in the first intake port in accordance with an engine operating condition,   wherein the second intake port has an axis with at least a major part contained in a first vertical plane inclined relative to a second vertical plane to form a first predetermined angle, the first vertical plane approaching the center axis of the piston while becoming closer to the center axis of the piston than the second vertical plane, the first and second vertical planes being vertical to the block deck of the cylinder block, the second vertical plane passing through the first intake valve and first exhaust valve and being perpendicular to a third vertical plane containing the center axes of the cylinders, the first intake valve and the first exhaust valve being located respectively on opposite sides of the third vertical plane,   wherein the fuel injector is arranged such that fuel injected through the fuel ejection hole has first and second sections which are on opposite sides of a plane containing the axis of the fuel ejection hole, the first section being located closer to the spark plug than the second section, the first section having a higher flow velocity than the second section.   
     
     
       27. A cylinder direct injection spark-ignition engine as claimed in claim 26, wherein the first vertical plane is generally tangential to a periphery of the circular cavity. 
     
     
       28. A cylinder direct injection spark-ignition engine as claimed in claim 26, wherein the first vertical plane is generally parallel with a fourth vertical plane containing a tangent line of a periphery of the circular cavity. 
     
     
       29. A cylinder direct injection spark-ignition engine as claimed in claim 26, wherein the tip end section of the spark plug is disposed above a peripheral portion of the circular cavity and located On an opposite side of the first vertical plane with respect to the second vertical plane. 
     
     
       30. A cylinder direct injection spark-ignition engine as claimed in claim 26, wherein the first vertical plane passes through a space between a periphery of the circular cavity and the spark plug. 
     
     
       31. A cylinder direct injection spark-ignition engine as claimed in claim 24, wherein the axis of the fuel injector extends into the circular cavity, the fuel injector being located between the first and second intake ports. 
     
     
       32. A cylinder direct injection spark-ignition engine as claimed in claim 26, wherein the swirl control valve is arranged to substantially block the first intake port under a predetermined engine operating condition in which stratified charge combustion occurs in the combustion chamber. 
     
     
       33. A cylinder direct injection spark-ignition engine as claimed in claim 26, wherein the first and second intake ports are located on an opposite side of the third vertical plane with respect to the first and second exhaust ports. 
     
     
       34. A cylinder direct injection spark-ignition engine as claimed in claim 26, wherein the first predetermined angle is at least 5 degrees and smaller thin 15 degrees. 
     
     
       35. A cylinder direct injection spark-ignition engine as claimed in claim 26, wherein the at least a major part of the axis of the second intake port forms a second predetermined angle relative to the block deck of the cylinder block, the second predetermined angle being within a range of larger than 30 degrees and smaller than 40 degrees. 
     
     
       36. A cylinder direct injection spark-ignition engine as claimed in claim 26, wherein the axis of fuel injector forms a third predetermined angle relative to the block deck of the cylinder block, the third predetermined angle being within a range of from 35 degrees to 45 degrees. 
     
     
       37. A cylinder direct injection spark-ignition engine, comprising: a cylinder head that defines a portion of a combustion chamber and that holds a spark plug;   a cylinder block having a cylinder;   at least one intake valve and at least one exhaust valve movably disposed on the cylinder head;   a piston movably disposed in the cylinder so as to define a portion of the combustion chamber, the piston having a piston crown with a generally circular cavity having a center axis, which is offset from a center axis of the piston toward the intake valve;   a spark plug having a tip end section disposed above a part of a peripheral portion of the circular cavity, which part is located closer to the center axis of the piston than to a periphery of the piston;   a valve that generates a swirl of intake air in the combustion chamber; and   a fuel injector that directly injects fuel into the combustion chamber, the fuel injector having an axis inclined relative to a plane forming a right angle with a longitudinal axis of the combustion chamber and that injects fuel from an intake valve side of the combustion chamber toward an exhaust valve side of the combustion chamber, the fuel injector having a fuel ejection hole with an axis inclined relative to the axis of the fuel injector toward the spark plug;   wherein the fuel injector is arranged such that fuel injected through the fuel ejection hole has first and second sections which are on opposite sides of a plane containing the axis of the fuel ejection hole, the first section being located closer to the spark plug than the second section, the first section having a higher flow velocity than the second section.   
     
     
       38. A cylinder direct injection spark-ignition engine, comprising: intake and exhaust valves movably disposed on a cylinder head which defines a portion of a combustion chamber; and   a fuel injector valve for directly injecting fuel into the combustion chamber, the fuel injector valve having an axis inclined relative to a bottom surface of the cylinder head and that gradually approaches the bottom surface in a direction extending from an intake valve side of the combustion chamber toward an exhaust valve side of the combustion chamber, the fuel injector valve having a fuel ejection hole with an axis inclined relative to the axis of the fuel injector valve so as to form a first angle which is smaller than a second angle formed by the axis of the fuel injector valve and the bottom surface of the cylinder head,   wherein an angle formed by the axis of the fuel ejection hole and the bottom surface of the cylinder head is smaller than the second angle, and   wherein the fuel injector valve is arranged such that fuel injected through the fuel ejection hole is formed into a shape of a spray cone having first and second sections which are opposite to each other with respect to a plane containing the axis of the fuel ejection hole, the first section being located closer to a surface of the cylinder head defining a portion of he combustion chamber than the second section, the first section having a higher flow velocity than the second section.   
     
     
       39. A cylinder direct injection spark-ignition engine, comprising; a cylinder head that defines a portion of a combustion chamber and that holds a spark plug;   at least one intake valve and at least one exhaust valve movably disposed on the cylinder head; and   a fuel injector that directly injects fuel into the combustion chamber, the fuel injector laving an axis inclined relative to a plane forming aright angle with a longitudinal axis of the combustion chamber and that injects fuel from an intake valve side of the combustion chamber toward an exhaust valve side of the combustion chamber, the fuel injector having a fuel ejection hole with an axis inclined relative to the axis of the fuel injector,   wherein an angle formed by the axis of the fuel ejection hole and the plane is smaller than an angle formed by the axis of the fuel injector valve and the plane, and   wherein the fuel injector is arranged such that fuel injected through the fuel ejection hole has first and second sections on opposite sides of a plane containing the axis of the fuel ejection hole, the first section being located closer to the spark plug than the second section, the first section having a higher flow velocity than the second section.   
     
     
       40. A cylinder direct injection spark-ignition engine, comprising: a cylinder head that defines a portion of a combustion chamber and that holds a spark plug;   at least one intake valve and at least one exhaust valve movably disposed on the cylinder head; and   a fuel injector that directly injects fuel into the combustion chamber, the fuel injector having an axis inclined relative to a plane forming a right angle with a longitudinal axis of the combustion chamber and that injects fuel from an intake valve side of the combustion chamber toward an exhaust valve side of the combustion chamber, the fuel injector including means for injecting the fuel such That the fuel has first and second sections, the first section being located closer to the spark plug than the second section, and the first section having a higher flow velocity than the second section.